Roll-off bins are widely used for a variety of purposes, such as (to name only a few) for collecting waste and debris from construction and demolition sites, general industrial waste, and hazardous waste. After being loaded with such waste materials, the bins are transported to appropriate disposal sites where they are emptied.
Roll-off bins are so-named because they typically have wheels at one end so that they can be loaded onto tilting flatbed trailers (or “roll-off trucks”), or onto non-tilting flatbed trailers using suitable ramps, then transported to an industrial site (for example) where they are rolled off into position to be filled with waste materials. Roll-off bins are typically of rectangular configuration, with a generally flat rectangular floor structure and a pair of longitudinal sidewalls extending between a pair of transverse endwalls, so as to define an open-top waste containment chamber. Especially on larger roll-off bins, one of the endwalls (typically at the wheeled end of the bin) may be hinged, either vertically or horizontally, to facilitate rapid emptying—for example, by opening the hinged endwall while the loaded bin is still securely mounted on a roll-off truck which then tilts the bin so that its contents slide out the open endwall by gravity.
Roll-off bins can vary greatly in size. They commonly have a nominal width of 8 feet, corresponding to the typical maximum permissible width for highway vehicles without requiring special permits. Common volumetric capacities for roll-off bins range from 10 to 40 cubic yards, depending on bin length and bin wall height.
Roll-off bins typically require a lid for one or more reasons, such as for protection of bin contents from the weather, for prevention of loss of bin contents during transport, for general security reasons, and for the safety of workers and the public. Numerous types of roll-off bin lids are known in the prior art. The simplest types are flat lids hinged along the top of one of the bin sidewalls, without the provision of any mechanism for opening and closing the lid. For light-duty waste bins (such as the smaller plastic refuse bins commonly seen in residential complexes for collection of household waste), such simple hinged lids may be quite satisfactory, since they typically are relatively light in weight, and thus can be easily opened by a single person, and can close by gravity with minimal risk of inadvertent personal injury. However, larger waste bins are generally made from steel, for both structural strength and durability. Accordingly, the lids for such bins can be quite heavy, and as a practical matter they will typically require some sort of mechanism to facilitate efficient opening and closing, while providing protection against injury that could be caused by inadvertent and uncontrolled closing of the lid.
For these reasons, it is common for hinged lids for roll-off bins to use a winch apparatus for opening and closing the lid, operated either manually or by an electric motor. Such apparatus typically entails the provision of a gin pole or other auxiliary structure to support associated pulleys and cables. Other apparatus for opening and closing heavy roll-off bin lids may use hydraulic cylinders, which can be arranged to avoid the need for auxiliary structure extending above the bin walls. However, roll-off bins are very often used in circumstances and locations where electric or hydraulic operation of bin lids is not feasible or practical, so for practical reasons it commonly must be possible for roll-off bin lids to be opened and closed manually.
Regardless of the particular type of mechanisms that may be used to open and close them, hinged roll-off bin lids have a significant drawback in that when they are in an open or partially-open position, they will project above the bin walls and thus be exposed to wind forces. Accordingly, the lids, hinge mechanisms, and associated structural elements must be designed to withstand strong wind forces that might otherwise damage these components, necessitating costly repairs and putting the bins out of service. As a result, the lids will be heavier and costlier than they would be if they did not need to be designed for wind forces.
Furthermore, even hinged lids that have associated winch mechanisms or electrical or hydraulic operating systems can present a safety hazard in the case of failure of one or more components of such mechanisms or systems (for example, breakage of a winching cable, or loss of hydraulic pressure). In such scenarios, serious personal injury could result from the sudden uncontrolled closing of a heavy hinged lid.
These disadvantages and risks can be avoided by using rolling lids, many examples of which can be seen in prior art bins. In common types of rolling lids, the lid has wheels that travel in or on horizontal tracks, such that the lid can be displaced laterally away from one bin sidewall toward the other sidewall by means of an associated operating mechanism (such as a rack-and-pinion gear arrangement) operated manually by means of a crank. The rolling lid has a longitudinal pivot axis at approximately its mid-width (i.e., parallel to the sidewalls), and this pivot axis moves laterally with the lid. The lid will remain essentially horizontal until it has been laterally displaced far enough that the pivot axis lies outboard of one of the sidewalls. At that point, the lid can be pivoted 90 degrees such that half of its width is disposed against the exterior of that sidewall, with the other half of its width projecting above the top of the sidewall.
One beneficial feature of the rolling lid described above is that it opens the top of the bin to its full width. Another beneficial feature is that it largely eliminates the above-noted safety risks associated with hinged lids. However, one significant practical drawback of this lid design is that its overall width must be greater than the width of the bin itself, because the tracks for the lid must extend a certain distance beyond at least one of the bin sidewalls to facilitate rotation of the lid into a vertical plane. Accordingly, the maximum allowable width of the bin itself, and its volumetric capacity (for a given bin length and height), will be less than for other bin designs in order to stay within maximum vehicle load widths under many highway transportation regulations (i.e., typically 8 feet). Another drawback of the rolling lid is that half of its surface area still projects above the bin walls and thus will be exposed to wind loads.
For the foregoing reasons and others, there is a need for improved waste container lid designs that will:                eliminate or significantly reduce potential safety hazards associated with conventional hinged bin lids;        eliminate or minimize bin lid exposure to wind forces when the lid is in an open position; and        facilitate maximization of usable bin width while complying with regulated vehicle load width restrictions.        